Automatic ignition and gas shutoff mechanism



x July 6, 1943- J. H. HAMMOND, JR

AUTOMATIC IGNITION AND GAS SHUT-OFF MECHANISM Filed March 19, 1941 R b mW flm T.. .mAfl WH mm N H m. I I HHQ mi Patented July 6, 1943 um'rao STATES PATENT OFFICE AUTOMATIC IGNITION AND GAS SHUTOFF MECHANISM John Hays Hammond, Jr., Gloucester, Mass.

Application March 19, 1941, Serial No. 384,065

1 Claim. (Cl. 158-28) This invention relates to ignition systems for burners and more particularly to an improved system for automatically igniting a gas or oil flame when the supply of fuel is turned on or for reigniting the flame should the same become extinguished while the supply-of fuel is continued.

The invention further relates to means for shutting off the supply of fuel if the flame is accidentally extinguished or if the fuel fails to ignite after it has been turned on.

The invention also consists in certain new and original features of construction and combinations of parts hereinafter set forth and claimed.

Although the novel features which are believed to be characteristic of this invention will be particularly pointed out-in the claim appended hereto, the invention itself, as to its objects and advantages, the mode of its operation and the manner of its organization may be better understood by referring to the following description, taken in connection with the accompanying drawing forming a part thereof, in which The single figure illustrates diagrammatically the invention as applied to a gas firing system.

In the following description and in the claim parts will be identified by specific names for convenience, but they are intended to be as generic in their application to similar parts as the art will permit.

Referring to the embodiment of the invention shown in the drawing, a combustion chamber H is provided with a fuel jet i2 secured to the end of a supply pipe i3 which passes through the wall of the combustion chamber and is connected to any suitable fuel supply not shown. It is to be understood that the combustion chamber ii and jet it are illustrative of any fiuid fuel burner such as a range, furnace, refrigerator or the like supplied by gaseous or liquid fuel.

Connected in the supply pipe l3 are two valves 35 and it for controlling the supply of fuel to the jet B2. The valve i5 comprises a. casing I? in which reciprocates a valve stem i8 provided with an aperture 59 which permits the free flow of fuel when the valve stem I8 is in its operative position as shown in the figure. Secured to the upper end of the valve stem i8 is a cap 26 between which and the valve casing H is a compression spring RI. The lower end of the valvevstem id is provided with a notch 22 which is normally engaged by plunger 23 which forms the core of a solenoid 25. Secured to the plunger 23 is a collar 26 between which and the solenoid 25 is a compression spring 21.

The valve it comprises a casing 29 in which reciprocates a valve stem 30 provided with an aperture 3| which permits the free flow of fuel when the valve stem is in its operative position as shown in the figure. Secured to but insulated from the lower end of the valve stem 30 is a contact block 32. Secured to the upper end of the valve stem 3llis a piston 33 which reciprocates in a cylinder 35, the upper end of which communicates by means of a pipe 36 with the pipe I3. Mounted between the piston 33 and the lower end of the cylinder is a compression sprin 37.

Mounted in the retort i I is a thermostatic element 39 of standard and well known construction, which is provided with a shaft 40 extending A second fixed contact also engages contact,

block 32 and is connected through the winding of a relay 46 to a fixed contact 41 which engages the contact arm 4| when the thermostatic device 39 is not receiving heat. Shunted across the winding of the relay 46 is a coil 48 which surrounds a bi-metallic element 49 which is mounted in abracket 50 and which is electrically connected to one side of the battery 42. The element 69 is so constructed that when it is heated by the passage of an electric current through the winding 68, it will gradually bend to the left until it engages a fixed contact 5| which is connected a high potential source 53 to two electrodes 55 and 58 which are located adjacent to the jet i2 and function to ignite the flame 51.

Operation The mechanism i shown in the figure as in full operation with fuel from a source not shown being supplied by the pipe i3 to the jet l2 where it is burned to produce a flame 51. The valve i5 is held in the open position by means of the plunger 23 which engages the notch 22, and the valve [6 is held in the open position by the fuel pressure on the top of the piston 33. The themestatic device 39, receiving heat from the flame 51, has rotated the contact arm 4! so that it does not engage the contact 41.

If for any reason the supply of fuel to the pipe l3 should be cut off or should drop below a pre- Secured to determined pressure the piston 33 will be moved upward under the action 'of the spring 31 so as to close the valve l8, open contacts 43 and 45 and extinguish the flame 51 completely. As soon as the flame 51 has been extinguished, the thermostatic device 39 will cool causing the contact arm 4| to be rotated in a clockwise direction to engage the contact 41. The circuit is not completed by the contact 41, however, while the contact block 32 remains elevated. The mechanism remains in this position with the fuel cut of! by the valve I 5 until the fuel pressure again becomes sufficient to open the valve It.

When the supply of fuel is resumed, the piston 33 will be moved downward due to the pressure of the gas in cylinder 35 thus opening valve i6 and engaging contacts 43 and 45. This closes the circuit from the battery 42, contact arm 4|,

- contact 41, relay 4B and coil 48 in parallel, contact 45, contact block 32 and contact 43 back to battery 42. The energiz'ation of the relay 46 closes the circuit from the high potential source 53 to the electrodes 55 and 55 forming an arc at these electrodes which ignites the fuel issuing from the Jet I2 to form the flame 51. The heat from the flame 51, causes the contact arm 4| to be rotated in a counter-clockwise directiomthus opening the circuit at the contact 41. This breaks the circuit thru the relay 45 and coil 48, thus extinguishing the are between the electrodes 55 and 58, and rendering the control circuit ineffective until the flame 51 is again extinguished.

The mechanism is then in its normal operating condition as shown in the figure.

If for some reason the fuel should fail to ignite the thermostatic device 39 holds the contact arm 4| in engagement with the contact 41, thus allowing current to continue to flow thru the coil 43, for heating the same. The heat from the coil 48 will be transmitted to the bi-metallic element 49 causing it to bend to the left until, after a predetermined interval of time, it will engage the contact thus closing a circuit from the battery 42, element 49, contact 5| and solenoid back to battery 42. The energization of the solenoid 25 will cause the plunger 23 to be moved to the right thus releasing the valve stem i8 which will be moved upward under the action of the spring 2| to close the valve i5 and shut off the supply of fuel. The thermostatic elements 39 and 49 are designed to allow the normal time for ignition before the contact 5| is closed so that in normal operation the flame becomes ignited and the contact 41 is opened before the contact 5| has time to close.

When the supply of fuel is shut off by the valve i5, the valve it automatically closes thus opening the contacts 43 and 45 which will break the circuit thru the relay 46 and the coil 48, thus extinguishing the ignition arc and de-energizing.

the element 40 which then turns to its normal' position and opens the contact 5|. The valve i5 will remain in the closed position until it is manually opened by depressing cap 24. The cycle of operations previously described will then be repeated.

If, while the mechanism is in'operation, the flame 51 should be accidentally extinguished or blown out the thermostaticdevice iii-will cool off, closing contact 41 to reignite the flame 51, and if this should not be accomplished in a predetermined time the valve [5 is closed in a manner already described. v

If it is desired to extinguished the flame 51 the plunger 25 is manually moved to the right thus closing valve l5 and putting the entire mechanism into an inoperative condition. When it is desired to relight the flame 51, the cap 20 is depressed manually, thus opening valve 20, which as previously described will open valve l5 and energize the ignition circult.

Although only a specific form in which this invention may be embodied has been shown herein, it is to be understood that the invention is not limited to any specific construction but may be embodied in various forms without departing from the spirit of the invention or the scope of the appended claim.

What is claimed is:

A system of the class described comprising a fluid fuel burner, a fuel supply pipe supplying fuel' thereto for combustion, ignition means for said burner including an energizing circuit, a thermostatic switch exposed to the heat of the burner and connected to close said energizing circuit when said burner is cold, a normally open valve in said fuel supply pipe, electro-magnetic trip means to close said valve and a delay action relay connected to be energized with said ignition means and to actuate said trip means after a predetermined interval, said thermostatic switch being connected to de-energize said delay action relay and said energizing circuit when the burner becomes hot, a pressure controlled valve in said fuel supply pipe between said first valve and said burner actuated by fuel pressure to close in response to failure of said pressure and to open when said pressure exceeds a predetermined value, means associated with said last valve to open the energizing circuit for said ignition means and the circuit to said delay action relay when said last valve is closed and to close said circuits when said last valve is open, whereby the ignition means is automatically rendered operative whenever the flame is extinguished with the fuel supply open, the fuel supply is automatically cut off if the burner fails to ignite, and the ignition means is again rendered operative when the flrst valve is reopened.

JOHN HAYS HAMMOND, Jn. 

